Students fish for mercury levels
After spending time Friday wading in the Thomson Reservoir emptying nets and then dissecting a sucker fish, Carlton junior Dom Phaller said he would love to be a fisheries biologist someday, but he isn't sure he wants to eat any more fish for awhile.
"I guess it would depend on what we find out about the mercury levels," Phaller said, referring to the five fish samples he and his classmates in Tracy Bockbrader's advanced chemistry class were sending off to be tested.
Friday was the culmination of the classroom's study of mercury facts and toxicity, a time when they got to see how the knowledge they gained in the classroom could be applied in the field.
After three of their classmates, along with fisheries biologist Josh Dumke and field technician Mick Pierce from the University of Minnesota-Duluth's Natural Resources Research Institute (NRRI), emptied the two different nets, five different groups of students were each given a dead sucker and a plastic bag. Inside the bag was a filet knife, tweezers, a zip tie and ID tag, foil wrap, plastic gloves and information sheets for data.
After donning the gloves, students measured and weighed each fish, before filleting them and cutting a finger-sized chunk of flesh off to be sent in for mercury testing. They also removed several scales for testing and basically turned each sucker's head inside out searching for the otolith, which Dumke also called "ear stones."
"It feels like you're tapping glass," he told the students after advising them they'd have to feel around with metal tweezers to find the tiny bones inside the ear.
Both the otoliths and the scales would be used to try to identify the age of the fish, Dumke said. He explained the otolith acquires a growth ring — similar to a tree trunk — that can be used to help figure age.
There were no audible "yucks" from the students, who divided themselves into groups and different duties in a fairly businesslike manner.
Dumke explained that mercury content in fish tissue is a little bit higher than typical in the lower sections of the St. Louis River (below the Fond du Lac dam), so collecting mercury concentration data from local waterbodies is a suitable topic for this area.
"Tracy's class get exposed to mercury bioaccumulation and biomagnification curricula in the classroom, and this has been a nice and relatively easy way to provide some experiential learning to students so they can be a part of some fish research," Dumke said, noting the experiment wouldn't be possible without the assistance of local business North Shore Analytical, who agreed to support this work by processing some fish tissue samples for total mercury for free.
The students should get the results of the testing back in a couple weeks.
"Apparently they haven't studied fish from this area since 1992, so this is needed," Bockbrader said.
The chemistry teacher said this is the second year her College-in-the-Schools chemistry students have participated in fish research with the NRRI. It's part of the Rivers2Lake Education Program at the Lake Superior Reserve, which helps teachers integrate the Lake Superior watershed into their curriculum using outdoor education and place-based learning.
"I like providing these hands on learning experiences to help them experience how science applies to real life," she said. "I believe students sometimes forget that there are people that use science skills in their careers and it's not all classroom facts and figures."
"This gives the students a chance to actually see mercury concentration research being performed from start to finish," Dumke said. "For me, it's an opportunity to inspire students to seek careers in the sciences, I get to perform a little research project, and it's fun!
"I would definitely do his job ... if it pays good," said Phaller.
Funding for the project is provided by the Duluth Superior Area Community Foundation Fund for the Environment.